The conventional method for sealing beer bottles or similar containers resides in providing a crown cap of metallic construction which is crimped into locking relation on the pouring mouth of the container. These, necessitate the use of a tool or bottle opener to uncrimp and remove the crown cap from the bottle, which obviously constitutes a disadvantage.
To solve this problem it has been suggested to use a twist-off crown cap threadedly engaged on the neck of the bottle that can be removed by hand without using a bottle opener or the like. However, this design suffers from a disadvantage in that the sharp projections on the skirt of the crown cap can cause injuries to fingers when attempting to twist-off the cap, and to the best knowledge of the present inventor, no satisfactory solution has been found to this problem yet.
Furthermore, containers with twist-off crown caps are prone to tampering because such closures can be removed and installed back on the container without causing any apparent damage to warn that the container has been tampered with.